How to tell if ductwork is bad?

Determining whether your home's heating and cooling ductwork has gone bad requires observing structural degradation, chronic comfort failures, and environmental red flags. Key warning signs include widespread physical damage such as severe crushing, torn flexible plastic outer jackets, heavy rust on metal trunk lines, and decaying fiberglass insulation. Furthermore, if you experience chronic room-to-room temperature imbalances that cannot be fixed by balancing dampers, soaring utility bills caused by massive energy leakage, or heavy dust and musty mold odors blowing from supply registers, your ducts are likely failing. You can troubleshoot by having a professional inspect your duct runs with a camera. You can verify that ductwork is bad when professional pressure testing confirms excessive leakage and physical inspection reveals unrepairable structural decay requiring total replacement.